1. Field of the Invention
This invention relates to apparatus for producing fuel/air mixtures for internal combustion engines. More particularly, the present invention relates to apparatus in which the heat of exhaust gases from the engine is utilized in an efficient manner to completely vaporize the fuel, thereby enabling production of an efficiently burning fuel/air mixture.
2. Description of the Prior Art
In a conventional carburetor, a stream of gasoline is aspirated into a draft of air in a venturi where it is dispersed into a mist of fine droplets. Despite years of development, the conventional carburetor is comparatively inefficient. Theoretically, the droplets vaporize to produce a gaseous fuel/air mixture. In actual practice, vaporization is often incomplete with the result that combustion is also incomplete, and unburned hydrocarbons pass into the exhaust and are wasted.
Numerous attempts have been made to develop alternative systems for producing fuel/air mixtures in which complete volatilization will be achieved. It has been proposed to use the heat of the exhaust gases from the engine to promote vaporization. For example see Giardini, et. al., U.S. Pat. No. 4,099,499; Goodspeed, U.S. Pat. No. 857,730; and Coffman, U.S. Pat. No. 1,267,185, in which the fuel line is passed through the exhaust conduit in order that the heat of the exhaust gases may promote vaporization. Rose, U.S. Pat. No. 3,931,801, and Reichhelm, U.S. Pat. No. 3,667,436, disclose systems in which the hot exhaust gases are passed into direct contact with the fuel in order to promote vaporization. In the system of Reichhelm, the hot exhaust gases are also passed into contact with the exterior of the gasification chamber and preheated air may optionally be passed through the gasification chamber in order to cleanse the chamber. Leshner, et al., U.S. Pat. No. 4,015,569, discloses a system in which volatile liquid fuel is passed through a chamber located in the exhaust conduit of an internal combustion engine and vaporized by the heat of the exhaust gas after which the fumes are mixed with combustion air and fed to the engine.
Lee, U.S. Pat. No. 3,911,881, discloses a system in which a fuel/air mixture from a carburetor is passed through a vaporization chamber which is heated by passing hot exhaust gases through an adjoining chamber. Harrow, et. al., U.S. Pat. No. 3,987,773, and Mills, U.S. Pat. No. 3,957,024, disclose systems in which a heat transfer fluid is used to convey heat from the hot exhaust gases to vaporize a liquid fuel in a stream of combustion air. Naylor, U.S. Pat. No. 4,003,356, discloses a system for vaporizing a liquid motor fuel in an air-free environment by passing it in heat exchange relation with the hot water from the engine cooling system. Beard, U.S. Pat. No. 3,447,511, teaches the use of heat from exhaust gases to generate fuel from crude oil. Morse, U.S. Pat. No. 961,152, and Westendarp, U.S. Pat. No. 858,046, disclose vaporization of heavy hydrocarbons, such as kerosene, by passing them in heat exchange relation with hot exhaust gases after which the fuel vapors are mixed with combustion air.
Despite the extensive efforts of the prior art to find a substitute for the conventional carburetor, conventional carburetors today remain the principal means utilized to produce fuel/air mixtures for internal combustion engines, notwithstanding all of the known disadvantages of such carburetors.